Re: v5.13-rcX regression - NULL pointer dereference - MFD and software node API

From: Andy Shevchenko
Date: Sun Jun 20 2021 - 14:28:37 EST


On Sun, Jun 20, 2021 at 7:36 PM Andy Shevchenko
<andy.shevchenko@xxxxxxxxx> wrote:
> On Sun, Jun 20, 2021 at 2:50 PM Dominik Brodowski
> <linux@xxxxxxxxxxxxxxxxxxxx> wrote:
> > Am Sun, Jun 20, 2021 at 02:19:44PM +0300 schrieb Andy Shevchenko:
> > > On Sun, Jun 20, 2021 at 11:36 AM Dominik Brodowski
> > > <linux@xxxxxxxxxxxxxxxxxxxx> wrote:
> > > >
> > > > Over a month ago, Andy Shevchenko reported and fixed a NULL pointer
> > > > dereference issue introduced by commit
> > > > 42e59982917a ("mfd: core: Add support for software nodes")
> > > > in v5.13-rc1:
> > > > https://lore.kernel.org/lkml/20210510141552.57045-1-andriy.shevchenko@xxxxxxxxxxxxxxx/
> > > >
> > > > A bisect shows that it is indeed commit 42e59982917a which causes boot to
> > > > fail due to a NULL pointer dereference on my work laptop,
> > >
> > > Can you, please, be more specific? E.g. where may I find the ACPI dump
> > > of your laptop, along with other information?
> > > What you may prepare is (all run under root user)
> > > 1. `acpidump -o laptop-$MODEL.dat` (the *.dat file)
> > > 2. `grep -H 15 /sys/bus/acpi/devices/*/status`
> > > 3. `dmesg`
> > > 4. `cat /proc/iomem /proc/ioport`
> > > 5. `lspci -nk -vv`
> > >
> > > (#2 and #3 are interesting to have in working and non-working cases)
> > >
> > > Perhaps a bug on the kernel bugzilla would be a good container for all these.
> > >
> > > Also it's not clear what exactly an Oops you have (I don't believe
> > > it's the same).
> >
> > Thanks for taking a look at this issue. As it's actually a panic during
> > boot which triggers before initramfs is ready, I can only provide the data
> > for the "working case", i.e. with the patch causing the regression already
> > reverted:
> >
> > https://bugzilla.kernel.org/show_bug.cgi?id=213511
> >
> > With commit 42e59982917a reverted, the system works just fine.
>
> Is it possible to have any traces of the panic to be logged / photoed / etc?

I'm just wondering (based on the idea behind my fix) if the commenting
out INT3446 ID entry in the intel-lpss-acpi.c will help boot this? If
so, you may try to bind it later to the driver and see the Oops.


--
With Best Regards,
Andy Shevchenko